When a driver is driving a vehicle, the driver may be required to make a difficult determination such as a determination of entry into an intersection. Development of a technique for automating such a determination and a driving operation based on a result of the determination has been promoted. It is, however, difficult to respond to an irregular situation by an automated determination, and a driver's determination is often required in the end. Further, a driver may feel dissatisfied or uneasy about a result of an automated determination.
Therefore, a technique for, when a driver himself makes a situation determination, assisting the situation determination by the driver is desired. Patent Literature (PTL) 1 (Japanese Unexamined Patent Application Publication No. 2006-79167) proposes a technique of issuing a warning when current vehicle information deviates from a predetermined determination criterion, for driving characteristic data stored in a memory.